Experts are putting a damper on rumors - spreading like wildfire on the Internet - that the blazes in Waldo Canyon and Black Forest were set by terrorists.

Still, they say, the threat of pyroterrorism is not something that can be ignored.

"The potential is always there for pyroterrorism," said Dick Mangan, owner of Blackbull Wildfire Services in Missoula, Mont. "It doesn't have to be foreign. It could be domestic, as well."

Mangan, former president of the International Association of Wildland Fire who retired from the U.S. Forest Service as the Fire and Aviation Program Leader at the Missoula Technology Development Center, downplayed pyroterrorism as the cause behind the recent spate of wildfires in Colorado.

"Just because somebody starts a fire, doesn't mean they are a terrorist," he said. "A terrorist has a political agenda. He is trying to strike fear or cause damage to a political institution for political reasons."

Nonetheless, pyroterrorism is on the radar for federal agencies.

In 2004, the FBI warned the National Interagency Fire Center of the possibility that Al-Quaeda had plans to start wildland fires in Montana, Wyoming, Utah and Colorado.

Robert Baird, deputy national fire director of Fire and Aviation Management for the U.S. Forest Service at said at a 2013 conference in San Diego that pyroterrorism "is a real threat. Anything we can do to reduce it is a real accomplishment."

Wildfires are among the most difficult blazes to investigate, experts say.

The most difficult part is finding where they started.

"Even if you think you can figure it out, then you have to prove it," Mangan said. "It takes a lot of work and there's a very skilled cadre of people that do that who are fire investigators."

If investigators plan to bring charges against someone or file a civil lawsuit, "you want to be right," he said. "You don't know what the government knows," Mangan said. "They may have inside information that they don't want revealed, or it may compromise a source that they still want to use."

Investigators searching for the cause of a wildfire essentially work backwards, said Bill Gabbert, managing editor of Wildfire Today.

"You have to look for the direction of the spread to see which way the fire is moving," he said. "So you have to work backwards."

The quicker the response, the easier it is to find the point of origin because it decreases the area investigators must peruse.

Once the point of origin is located, investigators must determine what started the fire, which, depending on the igniter, "can be fairly easy or hard."

"If they use a lighter and put it back in their pocket, it's hard," he said.

But arsonists also use devices that are left at the scene, sometimes something as tiny as a match.

"If you're lucky, you can find the match," Gabbert said. "Even if it's charred, it helps."